This invention relates to accessory carburetor-adjusting apparatus for fine tuning the engine operation of a personal jet-propelled watercraft while the watercraft is in the water at a race site and immediately preceding a racing or other competition event to obtain optimum engine performance under existing fuel and environmental conditions. Although the invention is particularly useful at competitive events, it is also important for the average recreational user to have his engine optimally tuned for quick throttle response during conventional maneuvers to avoid hesitations in engine operation which can often lead to instabilities and capsizing.
Fine tuning of the engine carburetion system over the range of throttle selections expected to be used during the competition is necessary for a variety of reasons, including: the high degree of competition in a variety of types of watercraft competitive events and the need for quick throttle response in dynamic abrupt maneuvers such as are performed in slalom and freestyle events; a variety of different geographical competition locations and related variations in altitude and seasonal temperature and humidity; and variations in the available gasoline and oil to be mixed as fuel for the watercraft engine. The classes of competition, such as those promoted by the International Jet Sports Boating Association, tend to equalize the competitors as far as the hardware requirements are concerned, i.e., the boats and engines may be essentially identical, so it is left to the prowess of the operator to have the engine optimally tuned and then optimally operate the watercraft to achieve victory in competition.
Typical off-the-shelf watercraft for recreational activities and various competitive categories have an engine compartment which is covered by a removable hood having a watertight sealed interface with the deck to preclude the entry of water into the engine area, and the tuning adjustments of the carburetor require removal of the hood to access manually adjustable needle valves on the carburator. The number of needle valves may vary and in connection with the preferred embodiment of the invention described herein the carburetor-adjusting accessory example may be used to adjust three such needle valves.